1 /*
2  *  (C) 2004-2009  Dominik Brodowski <linux@dominikbrodowski.de>
3  *
4  *  Licensed under the terms of the GNU GPL License version 2.
5  */
6 
7 #include <sys/types.h>
8 #include <sys/stat.h>
9 #include <fcntl.h>
10 #include <unistd.h>
11 #include <stdio.h>
12 #include <errno.h>
13 #include <stdlib.h>
14 
15 #include "cpupower.h"
16 #include "cpupower_intern.h"
17 
18 unsigned int sysfs_read_file(const char *path, char *buf, size_t buflen)
19 {
20 	int fd;
21 	ssize_t numread;
22 
23 	fd = open(path, O_RDONLY);
24 	if (fd == -1)
25 		return 0;
26 
27 	numread = read(fd, buf, buflen - 1);
28 	if (numread < 1) {
29 		close(fd);
30 		return 0;
31 	}
32 
33 	buf[numread] = '\0';
34 	close(fd);
35 
36 	return (unsigned int) numread;
37 }
38 
39 /*
40  * Detect whether a CPU is online
41  *
42  * Returns:
43  *     1 -> if CPU is online
44  *     0 -> if CPU is offline
45  *     negative errno values in error case
46  */
47 int cpupower_is_cpu_online(unsigned int cpu)
48 {
49 	char path[SYSFS_PATH_MAX];
50 	int fd;
51 	ssize_t numread;
52 	unsigned long long value;
53 	char linebuf[MAX_LINE_LEN];
54 	char *endp;
55 	struct stat statbuf;
56 
57 	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u", cpu);
58 
59 	if (stat(path, &statbuf) != 0)
60 		return 0;
61 
62 	/*
63 	 * kernel without CONFIG_HOTPLUG_CPU
64 	 * -> cpuX directory exists, but not cpuX/online file
65 	 */
66 	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/online", cpu);
67 	if (stat(path, &statbuf) != 0)
68 		return 1;
69 
70 	fd = open(path, O_RDONLY);
71 	if (fd == -1)
72 		return -errno;
73 
74 	numread = read(fd, linebuf, MAX_LINE_LEN - 1);
75 	if (numread < 1) {
76 		close(fd);
77 		return -EIO;
78 	}
79 	linebuf[numread] = '\0';
80 	close(fd);
81 
82 	value = strtoull(linebuf, &endp, 0);
83 	if (value > 1)
84 		return -EINVAL;
85 
86 	return value;
87 }
88 
89 /* returns -1 on failure, 0 on success */
90 static int sysfs_topology_read_file(unsigned int cpu, const char *fname, int *result)
91 {
92 	char linebuf[MAX_LINE_LEN];
93 	char *endp;
94 	char path[SYSFS_PATH_MAX];
95 
96 	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/topology/%s",
97 			 cpu, fname);
98 	if (sysfs_read_file(path, linebuf, MAX_LINE_LEN) == 0)
99 		return -1;
100 	*result = strtol(linebuf, &endp, 0);
101 	if (endp == linebuf || errno == ERANGE)
102 		return -1;
103 	return 0;
104 }
105 
106 static int __compare(const void *t1, const void *t2)
107 {
108 	struct cpuid_core_info *top1 = (struct cpuid_core_info *)t1;
109 	struct cpuid_core_info *top2 = (struct cpuid_core_info *)t2;
110 	if (top1->pkg < top2->pkg)
111 		return -1;
112 	else if (top1->pkg > top2->pkg)
113 		return 1;
114 	else if (top1->core < top2->core)
115 		return -1;
116 	else if (top1->core > top2->core)
117 		return 1;
118 	else if (top1->cpu < top2->cpu)
119 		return -1;
120 	else if (top1->cpu > top2->cpu)
121 		return 1;
122 	else
123 		return 0;
124 }
125 
126 /*
127  * Returns amount of cpus, negative on error, cpu_top must be
128  * passed to cpu_topology_release to free resources
129  *
130  * Array is sorted after ->pkg, ->core, then ->cpu
131  */
132 int get_cpu_topology(struct cpupower_topology *cpu_top)
133 {
134 	int cpu, last_pkg, cpus = sysconf(_SC_NPROCESSORS_CONF);
135 
136 	cpu_top->core_info = malloc(sizeof(struct cpuid_core_info) * cpus);
137 	if (cpu_top->core_info == NULL)
138 		return -ENOMEM;
139 	cpu_top->pkgs = cpu_top->cores = 0;
140 	for (cpu = 0; cpu < cpus; cpu++) {
141 		cpu_top->core_info[cpu].cpu = cpu;
142 		cpu_top->core_info[cpu].is_online = cpupower_is_cpu_online(cpu);
143 		if(sysfs_topology_read_file(
144 			cpu,
145 			"physical_package_id",
146 			&(cpu_top->core_info[cpu].pkg)) < 0) {
147 			cpu_top->core_info[cpu].pkg = -1;
148 			cpu_top->core_info[cpu].core = -1;
149 			continue;
150 		}
151 		if(sysfs_topology_read_file(
152 			cpu,
153 			"core_id",
154 			&(cpu_top->core_info[cpu].core)) < 0) {
155 			cpu_top->core_info[cpu].pkg = -1;
156 			cpu_top->core_info[cpu].core = -1;
157 			continue;
158 		}
159 	}
160 
161 	qsort(cpu_top->core_info, cpus, sizeof(struct cpuid_core_info),
162 	      __compare);
163 
164 	/* Count the number of distinct pkgs values. This works
165 	   because the primary sort of the core_info struct was just
166 	   done by pkg value. */
167 	last_pkg = cpu_top->core_info[0].pkg;
168 	for(cpu = 1; cpu < cpus; cpu++) {
169 		if (cpu_top->core_info[cpu].pkg != last_pkg &&
170 				cpu_top->core_info[cpu].pkg != -1) {
171 
172 			last_pkg = cpu_top->core_info[cpu].pkg;
173 			cpu_top->pkgs++;
174 		}
175 	}
176 	if (!(cpu_top->core_info[0].pkg == -1))
177 		cpu_top->pkgs++;
178 
179 	/* Intel's cores count is not consecutively numbered, there may
180 	 * be a core_id of 3, but none of 2. Assume there always is 0
181 	 * Get amount of cores by counting duplicates in a package
182 	for (cpu = 0; cpu_top->core_info[cpu].pkg = 0 && cpu < cpus; cpu++) {
183 		if (cpu_top->core_info[cpu].core == 0)
184 	cpu_top->cores++;
185 	*/
186 	return cpus;
187 }
188 
189 void cpu_topology_release(struct cpupower_topology cpu_top)
190 {
191 	free(cpu_top.core_info);
192 }
193